This is one of the most convenient technologies, but, as it turns out, not always safe. In this article we will tell you how fingerprint recognition works, and why an ordinary password is still more secure.
The secret is in the minutiae
The principle of the fingerprint scanner is based on the analysis of minutiae. These are sections of the pattern where the lines change, for example:
- They break off,
- end and start again,
- make a sharp turn,
- converge,
- bifurcate,
- twisting in loops, etc.
Our prints are unique precisely because of the minutiae. So the main task of the scanner is to read them as accurately as possible.
How the data is recognized
When the technology first appeared, scanners took a picture of a finger and then compared it with the images in memory. The main problem was that if the finger was placed 0.5 cm below or above the initial scanning position, recognition would not work.
Another disadvantage of visual recognition is that you can simply attach a photo of the fingerprint to the scanner and thus easily fool it. After all, the technology will get the same image as the reference sample and open access. That’s why optical scanners cannot provide serious protection and are rarely used.
Modern scanners analyze minutiae rather than the overall appearance of lines. This is how they work now:
- They do a scan of the attached finger.
- Minutiae are detected and extracted.
- The information on the mutual positioning of the minutiae is coded and used to form a digital matrix.
- The matrix obtained is compared with those stored in the database.
- If the percentage of coincidence is higher than the specified value – the fingerprint is accepted and gives access to the smartphone.
Types of fingerprint scanners
There are four varieties:
Optical – located under the screen. Modern OLED matrixes transmit light from both sides, which is used by manufacturers to place a conventional optical scanner directly under the screen. It trivially takes photos (moreover it has poor quality because of noise in the form of matrix pixels), that is why it often makes mistakes, takes a long time to “think” and detects any dummy, for example, on tape, film, etc.
Non-contact optical scanners. A more advanced model of optical scanners. In this case, the finger is not attached to the scanner, but to the glass under which several cameras take pictures from different sides. It is no longer possible to fool with a photograph, since the cameras create a stereo image. Theoretically, the only way to bypass the protection is to use a manufactured 3D model of the finger.
Capacitive. The first fingerprint sensors in smartphones were exactly those, and their varieties are still used by manufacturers. How it works: The surface of the scanner is covered by a dense network of miniature semiconductors. When you put your finger on them, the protruding lines act on the conductors, causing the capacitance of the circuit to change. These changes form the digital pattern of the fingerprint.
The disadvantages of a capacitive scanner:
- If your fingers are wet, water droplets cause extra sensors to short out and interfere with proper recognition.
- This sensor is also easy to fool with a 3D printer.
Ultrasonic. Now this is the most advanced and reliable option, because such scanners collect information not only about minutes, but also about the pulse, and also build a volumetric model of the lines for greater accuracy of the result. Because of their high cost, they are not yet widespread: only a few Samsung models are equipped with ultrasound scanners.
Fingerprint vs. password: which is better?
The answer depends on your priorities. If speed and convenience are more important to you, use a scanner. This option is perfect if your phone or laptop doesn’t have anything super secret and super valuable. A fingerprint will also be enough as a child-proof device.
In the other case, we recommend using a password, because the scanner can be fooled in a dozen ways, while bypassing the password is only two: hacking or peeking. If you come up with a fairly complex combination and make sure that no one is watching you while you enter, it will be extremely difficult to crack this password.